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Related: Stuff You Should NEVER Cook In Cast Iron
And in fact, that’s what researchers writing for the Journal of the American Dietetic Association found when they tested more than 20 different foods before and after being cooked in cast iron. Acidic applesauce, for instance, went from having almost no iron to packing in more than 7 milligrams of the stuff. And the iron in tomato sauce, another acidic food, increased by more than 5 milligrams.
Still, it’s tough to calculate exactly how much iron the food you cook will actually absorb. Liquid-based foods and ones that are cooked longer—like tomato-based stews—tend to absorb more iron than drier foods or ones that are cooked quickly—like quick-cooking rice. “The longer you cook something in the pan, the more iron it will absorb,” Cording explains.
Learn two clever ways to keep your cast-iron skillet in great condition:
The age of your pan matters, too. “An older, well-seasoned pan develops a thin coating that makes the iron less reactive with food,” says Cording. In other words, a brand-new skillet will imbue your meal with more iron than your grandmother’s 50-year-old cookware that’s still kicking because you know how to season a cast-iron skillet like a pro.
All of this means that, yes, you’ll give your food a nutritional boost—and maybe a significant one—by cooking it in a cast iron skillet. But because it’s tough to tell exactly how much iron your body is actually absorbing, your skillet shouldn’t be a substitute for eating iron-rich foods.
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Instead, look at it as a bonus supplement. “If you consume a plant-based diet with beans, lentils, nuts, and leafy greens as your primary sources of iron, this would be a great way to enhance your intake,” says Cording. Ditto if you’re on medications that make it harder for your body to absorb iron (like antacids or calcium supplements),or if it’s that time of the month—since women tend to lose more iron when they have their periods.
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The one exception to the rule is if you have a condition like hereditary hemochromatosis, a disorder in which your body loads up too much iron. “If you’re at risk for getting too much iron, [using a cast iron skillet] may make it hard to tell just how much extra you’re getting each day, which could be dangerous,” Cording says. In cases like that, you’re better off sticking with stainless steel cookware instead.